powerpc/eeh: Fix crash when adding a device in a slot with DDW

commit 6a040ce72598159a74969a2d01ab0ba5ee6536b3 upstream.

The DDW code uses a eeh_dev struct from the pci_dev. However, this is
not set until eeh_add_device_late is called.

Since pci_bus_add_devices is called before eeh_add_device_late, the PCI
devices are added to the bus, making drivers' probe hooks to be called.
These will call set_dma_mask, which will call the DDW code, which will
require the eeh_dev struct from pci_dev. This would result in a crash,
due to a NULL dereference.

Calling eeh_add_device_late after pci_bus_add_devices would make the
system BUG, because device files shouldn't be added to devices there
were not added to the system. So, a new function is needed to add such
files only after pci_bus_add_devices have been called.

Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@linux.vnet.ibm.com>
Acked-by: Gavin Shan <shangw@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
[bwh: Backported to 3.2: adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

4 files changed, 34 insertions, 3 deletions

diff --git a/arch/powerpc/include/asm/eeh.h b/arch/powerpc/include/asm/eeh.h
index 66ea9b8b95c5..21165a4c759f 100644
--- a/arch/powerpc/include/asm/eeh.h
+++ b/arch/powerpc/include/asm/eeh.h
@@ -61,6 +61,7 @@ void __init pci_addr_cache_build(void);
  */
 void eeh_add_device_tree_early(struct device_node *);
 void eeh_add_device_tree_late(struct pci_bus *);
+void eeh_add_sysfs_files(struct pci_bus *);
 
 /**
  * eeh_remove_device_recursive - undo EEH for device & children.
@@ -105,6 +106,8 @@ static inline void eeh_add_device_tree_early(struct device_node *dn) { }
 
 static inline void eeh_add_device_tree_late(struct pci_bus *bus) { }
 
+static inline void eeh_add_sysfs_files(struct pci_bus *bus) { }
+
 static inline void eeh_remove_bus_device(struct pci_dev *dev) { }
 #define EEH_POSSIBLE_ERROR(val, type) (0)
 #define EEH_IO_ERROR_VALUE(size) (-1UL)
diff --git a/arch/powerpc/kernel/of_platform.c b/arch/powerpc/kernel/of_platform.c
index e1612dfb4a93..b10beef561bc 100644
--- a/arch/powerpc/kernel/of_platform.c
+++ b/arch/powerpc/kernel/of_platform.c
@@ -91,6 +91,9 @@ static int __devinit of_pci_phb_probe(struct platform_device *dev)
 	/* Add probed PCI devices to the device model */
 	pci_bus_add_devices(phb->bus);
 
+	/* sysfs files should only be added after devices are added */
+	eeh_add_sysfs_files(phb->bus);
+
 	return 0;
 }
 
diff --git a/arch/powerpc/kernel/pci-common.c b/arch/powerpc/kernel/pci-common.c
index 458ed3bee663..a3cd94948468 100644
--- a/arch/powerpc/kernel/pci-common.c
+++ b/arch/powerpc/kernel/pci-common.c
@@ -1536,11 +1536,14 @@ void pcibios_finish_adding_to_bus(struct pci_bus *bus)
 	pcibios_allocate_bus_resources(bus);
 	pcibios_claim_one_bus(bus);
 
+	/* Fixup EEH */
+	eeh_add_device_tree_late(bus);
+
 	/* Add new devices to global lists.  Register in proc, sysfs. */
 	pci_bus_add_devices(bus);
 
-	/* Fixup EEH */
-	eeh_add_device_tree_late(bus);
+	/* sysfs files should only be added after devices are added */
+	eeh_add_sysfs_files(bus);
 }
 EXPORT_SYMBOL_GPL(pcibios_finish_adding_to_bus);
 
diff --git a/arch/powerpc/platforms/pseries/eeh.c b/arch/powerpc/platforms/pseries/eeh.c
index 565869022e3d..389e06b2f1f1 100644
--- a/arch/powerpc/platforms/pseries/eeh.c
+++ b/arch/powerpc/platforms/pseries/eeh.c
@@ -1238,7 +1238,6 @@ static void eeh_add_device_late(struct pci_dev *dev)
 	pdn->pcidev = dev;
 
 	pci_addr_cache_insert_device(dev);
-	eeh_sysfs_add_device(dev);
 }
 
 void eeh_add_device_tree_late(struct pci_bus *bus)
@@ -1257,6 +1256,29 @@ void eeh_add_device_tree_late(struct pci_bus *bus)
 EXPORT_SYMBOL_GPL(eeh_add_device_tree_late);
 
 /**
+ * eeh_add_sysfs_files - Add EEH sysfs files for the indicated PCI bus
+ * @bus: PCI bus
+ *
+ * This routine must be used to add EEH sysfs files for PCI
+ * devices which are attached to the indicated PCI bus. The PCI bus
+ * is added after system boot through hotplug or dlpar.
+ */
+void eeh_add_sysfs_files(struct pci_bus *bus)
+{
+	struct pci_dev *dev;
+
+	list_for_each_entry(dev, &bus->devices, bus_list) {
+		eeh_sysfs_add_device(dev);
+		if (dev->hdr_type == PCI_HEADER_TYPE_BRIDGE) {
+			struct pci_bus *subbus = dev->subordinate;
+			if (subbus)
+				eeh_add_sysfs_files(subbus);
+		}
+	}
+}
+EXPORT_SYMBOL_GPL(eeh_add_sysfs_files);
+
+/**
  * eeh_remove_device - undo EEH setup for the indicated pci device
  * @dev: pci device to be removed
  *